Pyrite marcasite

NiAs and structures related to those adopted by FeS2 (marcasite, pyrites, loellingite, etc.). 

Sanru aguilarite, naumannite, polybasite, pyrargyrite, stephanite electrum, miargyrite, chalcopyrite, fahore, arsenopyrite, marcasite, pyrite, sphalerite, stibnite cinnabar quartz, adularia, kaolinite, sericite, calcite... 

Yatani argentite electrum, chalcopyrite, marcasite, pyrite, pyrrhotite, galena, sphalerite quartz, adularia, chlorite, sericite, rhodochrosite... 

Osorezan coloradoile, krennerite marcasite, pyrite, orpiment, realgar quartz, barite... 

Suzaki calaverite, hessite, kawazulite, kostoviie, krennerite, native tellurium, petzite, poubaite, sylvanite clausthalite. kawazulite, native tellurium, poubaite, pyrite chalcopyrite, marcasite, pyrite, sphalerite quartz, barite, anatase... 

All of the samples analysed showed, as expected, that the major minerals are quartz, kaolinite, marcasite/pyrite and gypsum. In general the quartz is present in two distinct size ranges 500 ym and 50 ym. 

Based on highly accurate adiabatic-shield calorimetry measurements, Gronvold and Westrura ( ) reported that the enthalpy of transformation of marcasite to pyrite is -1.05 0.05 kcal raol" at 700 K. The adopted value of AjH (298.15 K) is selected to reproduce this enthalpy of reaction within the reported uncertainty. Lipin et al. (2), based on combustion calorimetry, reported a value of -5.6 kcal mol" for the marcasite-pyrite transformation at 298.15 K. Due to the state of the art in combustion calorimetry at the time of this measurement and uncertainty in the products (oxides of sulfur), this value must have a high uncertainty and is given no weight in our selection process. 

Six iron-sulfur minerals are stable enough to exist in nature all contain the ferrous (Fe +) form of iron. Those minerals with iron-to-sulfur ratios of 1 1 (FeS) are mackinawite and pyrrhotite. Those with iron-to-sulfur ratios of 3 4 0 0384) are greigite and smythite. All the iron sulfides with ratios of 1 1 and 3 4 are soluble in mild acids with formation of H2S. Those minerals with iron-to-sulfur ratios of 1 2 (FeSj) are pyrite and marcasite. Pyrite and marcasite are distinguished from the other four iron sulfides by their insolubility in concentrated HCl. Pyrite is highly pH- and temperature-stable. Due to this, it is found often in nature. This inertness also makes pyrite a desirable reaction product for sulfide removal using an iron-based scavenger. Various iron sulfides can be formed chemically from iron compounds reacting with soluble sulfides at ambient conditions in aqueous systems. The specific reaction conditions control both the products formed and the rate of reaction. 

Bismuth group Metal pigments Bismuthinite Marcasite Pyrite... 

Copper group Copper sulfides group Ccpperfll) sulfide Galena Marcasite Pyrite Tenorite... 

Iron group Marcasite Pyrite Copperas-, Egyptian blue-, Lapis lazuli, Misy MacIntyre (1992) 18964, 18969, 19013 Pliny (1st cent AD/Rackham, 1952) XXXIV.C.31 Scott (2002) 229, 260 Terry (1893)26... 

Many accessory minerals present in a elay influence its properties in the plastic and hardened states. Some of the organic and inorganic materials that may be present in elays inelude elarin, vitrain, marcasite, pyrite, quartz, gypsum, limestone, and dolomite. Their presence is indicated by endothermal peaks caused by deearbonation or exothermic peaks caused by oxidation. DTA curves of some of the accessory materials that may be present in a clay are shown in Fig. lO.P ... 

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